Details
The behavior of save state of sketch is different in modeling and drafting
Modeling
Save the part with sketch is active.
The sketch is inactive when the part is reopened.
Drafting
Save the part with sketch is active.
The sketch remains active when the part is reopened.
Is it working as designed or a bug?
Solution
In Drafting application, the Sketch Task Environment remains active as per current design.
This is mentioned in documentation as well.
Per documentation
The sketch task environment remains continuously available while in the Drafting application and cannot be terminated
Hence the user has to execute "MB3->Finish Sketch" if they don't want it to remain active
Hardware/Software Configuration
Platform: INTL64
OS: windows
OS Version: 1064
Product: NX
Application: DESIGN
Version: V11.0.1
Function: SKETCHER
Ref: 002-8015440